With the game looking destined to finish as a draw, the big defender, who had been brought on to replace Lee Tomlin, hammered home a left-footed drive to put Boro in control.

Gazette writer Jonathon Taylor offers five observations from the game.

1) Dean Whitehead was the surprise name on the Boro team sheet - and the experienced battler was the team's Mr Reliable once again. Barring an early back pass which caused a moment of panic, he was rock solid along with Boro's other defensive trio. A superb option to have - but where is Ryan Fredericks?

2) Boro had to soak up some early Brentford pressure in the first half - but it was a textbook opening 45 minutes from Karanka's Boro. They allowed the Bees to come onto them, then clinically hit them on the break. The home fans were restless and Boro were bouncing at the break.

3) Dimi Konstantopoulos doesn't make many mistakes - but what a costly one it was to allow Andre Gray the easiest of equalisers. The Greek stopper can't afford to take any risks in such high-profile matches - but to his credit, he followed up his blunder with a world class save to deny Jonathan Douglas.

4) Boro once again showed courage in abundance throughout the second half, with Dani Ayala and Ben Gibson outstanding again. But credit for the defensive masterclass must also go to Adam Clayton and Grant Leadbitter, who were tireless shielding their back four.

5) what an unlikely hero as Venezuelan defender Fernando Amorebieta sent 1,600 Teessiders into dreamland. It was a magical moment that puts Boro 90 minutes away from Wembley. Time to take a breather - and then it's onto the Riverside next Friday